mirror of https://github.com/knative/docs.git
209 lines
6.1 KiB
Markdown
209 lines
6.1 KiB
Markdown
---
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title: "Hello World - Rust"
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linkTitle: "Rust"
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weight: 1
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type: "docs"
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---
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A simple web app written in Rust that you can use for testing. It reads in an
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env variable `TARGET` and prints "Hello \${TARGET}!". If
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TARGET is not specified, it will use "World" as the TARGET.
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## Prerequisites
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- A Kubernetes cluster with Knative installed. Follow the
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[installation instructions](../../../install/README.md) if you need to create
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one.
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- [Docker](https://www.docker.com) installed and running on your local machine,
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and a Docker Hub account configured (we'll use it for a container registry).
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## Steps to recreate the sample code
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While you can clone all of the code from this directory, hello world apps are
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generally more useful if you build them step-by-step. The following instructions
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recreate the source files from this folder.
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1. Create a new file named `Cargo.toml` and paste the following code:
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```toml
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[package]
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name = "hellorust"
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version = "0.0.0"
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publish = false
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[dependencies]
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hyper = "0.12.3"
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pretty_env_logger = "0.2.3"
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```
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1. Create a `src` folder, then create a new file named `main.rs` in that folder
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and paste the following code. This code creates a basic web server which
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listens on port 8080:
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```rust
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#![deny(warnings)]
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extern crate hyper;
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extern crate pretty_env_logger;
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use hyper::{Body, Response, Server};
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use hyper::service::service_fn_ok;
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use hyper::rt::{self, Future};
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use std::env;
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fn main() {
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pretty_env_logger::init();
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let mut port: u16 = 8080;
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match env::var("PORT") {
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Ok(p) => {
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match p.parse::<u16>() {
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Ok(n) => {port = n;},
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Err(_e) => {},
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};
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}
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Err(_e) => {},
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};
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let addr = ([0, 0, 0, 0], port).into();
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let new_service = || {
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service_fn_ok(|_| {
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let mut hello = "Hello ".to_string();
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match env::var("TARGET") {
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Ok(target) => {hello.push_str(&target);},
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Err(_e) => {hello.push_str("World")},
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};
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Response::new(Body::from(hello))
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})
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};
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let server = Server::bind(&addr)
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.serve(new_service)
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.map_err(|e| eprintln!("server error: {}", e));
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println!("Listening on http://{}", addr);
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rt::run(server);
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}
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```
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1. In your project directory, create a file named `Dockerfile` and copy the code
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block below into it.
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```docker
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# Use the official Rust image.
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# https://hub.docker.com/_/rust
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FROM rust:1.27.0
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# Copy local code to the container image.
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WORKDIR /usr/src/app
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COPY . .
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# Install production dependencies and build a release artifact.
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RUN cargo install
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# Run the web service on container startup.
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CMD ["hellorust"]
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```
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1. Create a new file, `service.yaml` and copy the following service definition
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into the file. Make sure to replace `{username}` with your Docker Hub
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username.
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```yaml
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apiVersion: serving.knative.dev/v1alpha1
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kind: Service
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metadata:
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name: helloworld-rust
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namespace: default
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spec:
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template:
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spec:
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containers:
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- image: docker.io/{username}/helloworld-rust
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env:
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- name: TARGET
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value: "Rust Sample v1"
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```
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## Build and deploy this sample
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Once you have recreated the sample code files (or used the files in the sample
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folder) you're ready to build and deploy the sample app.
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1. Use Docker to build the sample code into a container. To build and push with
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Docker Hub, enter these commands replacing `{username}` with your Docker Hub
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username:
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```shell
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# Build the container on your local machine
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docker build -t {username}/helloworld-rust .
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# Push the container to docker registry
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docker push {username}/helloworld-rust
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```
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1. After the build has completed and the container is pushed to Docker Hub, you
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can deploy the app into your cluster. Ensure that the container image value
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in `service.yaml` matches the container you built in the previous step. Apply
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the configuration using `kubectl`:
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```shell
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kubectl apply --filename service.yaml
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```
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1. Now that your service is created, Knative will perform the following steps:
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- Create a new immutable revision for this version of the app.
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- Network programming to create a route, ingress, service, and load balance
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for your app.
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- Automatically scale your pods up and down (including to zero active pods).
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1. To find the IP address for your service, enter these commands to get the
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ingress IP for your cluster. If your cluster is new, it may take sometime for
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the service to get asssigned an external IP address.
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```shell
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# In Knative 0.2.x and prior versions, the `knative-ingressgateway` service was used instead of `istio-ingressgateway`.
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INGRESSGATEWAY=knative-ingressgateway
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# The use of `knative-ingressgateway` is deprecated in Knative v0.3.x.
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# Use `istio-ingressgateway` instead, since `knative-ingressgateway`
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# will be removed in Knative v0.4.
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if kubectl get configmap config-istio -n knative-serving &> /dev/null; then
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INGRESSGATEWAY=istio-ingressgateway
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fi
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kubectl get svc $INGRESSGATEWAY --namespace istio-system
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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xxxxxxx-ingressgateway LoadBalancer 10.23.247.74 35.203.155.229 80:32380/TCP,443:32390/TCP,32400:32400/TCP 2d
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```
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1. To find the URL for your service, enter:
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```
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kubectl get ksvc helloworld-rust --output=custom-columns=NAME:.metadata.name,URL:.status.url
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NAME URL
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helloworld-rust http://helloworld-rust.default.example.com
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```
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1. Now you can make a request to your app and see the result. Replace
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`{IP_ADDRESS}` with the address you see returned in the previous step.
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```shell
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curl -H "Host: helloworld-rust.default.example.com" http://{IP_ADDRESS}
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Hello World!
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```
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## Removing the sample app deployment
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To remove the sample app from your cluster, delete the service record:
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```shell
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kubectl delete --filename service.yaml
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```
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